[native] Fix hermes throwing on nonexistant files

Summary: issue: https://linear.app/comm/issue/ENG-6929/sqlite-database-deletion-was-triggered-by-detecting-corrupted-database

Test Plan:
tested that if the file doesn't exist authoritativeKeyserverID is 256 and it is possible to logout and back in
Tested that if the file exists and authoritativeKeyserverID is correctly set

Checked that

const {
    authoritativeKeyserverID: keyserverID,
    // $FlowExpectedError: file might not exist
  } = require('./facts/authoritative_keyserver.json');

throws if the file doesn't exist, so authoritativeKeyserverID is not being set to undefined

Reviewers: michal, tomek

Reviewed By: tomek

Subscribers: ashoat

Differential Revision: https://phab.comm.dev/D11157